function ppeak_plot ( )

x = linspace ( 0, 1, 51 );
y = linspace ( 0, 1, 51 );
[ X, Y ] = meshgrid ( x, y );
Z = ppeak ( X, Y );
surf ( X, Y, Z, 'EdgeColor', 'None' );
title ( 'Genz Product Peak Function' )
xlabel ( '<---X--->' )
ylabel ( '<---Y--->' )
zlabel ( '<---Z--->' )

  return
end
function f = ppeak ( x, y )

  f = 1.0 ./ ( 2^(9/4)/sqrt(170) + ( x - 0.5 ).^2 ) ...
          ./ ( 2^(9/4)/sqrt(170) + ( y - 0.5 ).^2 ) ;

  return
end
